We’re targeting mid-July for the e-book release, with the softcover to follow later. The July timeframe is entirely contingent on several factors: editing, e-book and softcover production, and how significant the changes announced at WWDC 2015 are.

Checking in again since May! Great to hear your book is almost ready! Like Kristof, I really would prefer that book in Swift. I know I’m only speaking for myself, but whether or not your book is in Swift is a crucial point for me.

I respect that a lot of devs are using Swift now, and if I had it all to do again, I’d do the whole project in Swift. This release will be in Obj-C. Having said that, the sample code will be available under a pretty liberal license, so if someone wants to port it to Swift, I’d be open to that collaboration.

(I always code in Objective-C++ for the Apple platform for better cross-platform portability (and since I am a C++ nerd), so I can reuse BIG chunks of code on other platforms as well, and so Objective-C is great for me)

I would love to see some expansion of the compute kernel section. Specifically I’m interested in operating on large arrays of complex data in parallel. Getting structs into metal without copying is somewhat of a challenge.

Normally this error indicates you’re trying to run a Metal project in the iOS Simulator. Metal isn’t supported in the Simulator, so you’ll need to build with Generic Device or a physical device scheme selected.